Abstract
Colloidal Unimolecular Polymer (CUP) particles are spheroidal, 3-9 nm with charged groups on the surface and a hydrophobic core, which offer a larger surface water fraction to improve the analysis of its characteristics. Differential scanning calorimetry (DSC) was performed to determine the characteristics of surface water. These properties include the amount of surface water, the layer thickness, density, specific heat of the surface water above and below the freezing point of water, melting point depression of free water, effect of charge density and particle size. The charge density on the CUP surface was varied as well as the molecular weight which controls the particle diameter. The surface water is proportional to the weight fraction of CUP < 20%. Analogous to recrystallization the CUP particles were trapped in the ice when rapidly cooled but slow cooling excluded the CUP, causing inter-molecular counterion condensation and less surface water. The density of surface water was calculated to be 1.023 g/mL to 1.056 g/mL depending on the surface charge density. The thickness of surface water increased with surface charge density. The specific heat of surface water was found to be 3.04 to 3.07 J/g. K at 253.15 K and 3.07 to 3.09 J/g. K at 293.15 K. The average area occupied by carboxylate and ester groups on the CUP surface were determined.
Recommended Citation
P. Geng et al., "Thermodynamic Characterization of Free and Surface Water of Colloidal Unimolecular Polymer (CUP) Particles Utilizing DSC," Polymers, vol. 12, no. 6, article no. 1417, MDPI, Jun 2020.
The definitive version is available at https://doi.org/10.3390/polym12061417
Department(s)
Chemistry
Publication Status
Open Access
Keywords and Phrases
Colloidal unimolecular polymer (CUP); Cooling rate; Counterion condensation; Density; Differential scanning calorimetry (DSC); Heat of fusion; Melting point depression; Specific heat; Surface water; Thickness
International Standard Serial Number (ISSN)
2073-4360
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
01 Jun 2020
